// Elect chooses a seed node, and returns a connection to a cal.
// If this process is the seed, returns nil.
func elect(name, id, laddr string, b *doozer.Client) *doozer.Client {
// advertise our presence, since we might become a cal
nspath := "/ctl/ns/" + name + "/" + id
r, err := b.Set(nspath, 0, []byte(laddr))
if err != nil {
panic(err)
}
// fight to be the seed
_, err = b.Set("/ctl/boot/"+name, 0, []byte(id))
switch err {
case doozer.ErrOldRev:
// we lost, lookup addresses again
cl := lookupAndAttach(b, name)
if cl == nil {
panic("failed to attach after losing election")
}
// also delete our entry, since we're not officially a cal yet.
// it gets set again in peer.Main when we become a cal.
err := b.Del(nspath, r)
if err != nil {
panic(err)
}
return cl
case nil:
return nil // we are the seed node -- don't attach
}
panic(err)
}
func activate(st *store.Store, self string, c *doozer.Client) int64 {
w := store.NewWatch(st, calGlob)
for _, base := range store.Getdir(st, calDir) {
p := calDir + "/" + base
v, rev := st.Get(p)
if rev != store.Dir && v[0] == "" {
seqn, err := c.Set(p, rev, []byte(self))
if err != nil {
log.Println(err)
continue
}
w.Stop()
return seqn
}
}
for ev := range w.C {
// TODO ev.IsEmpty()
if ev.IsSet() && ev.Body == "" {
seqn, err := c.Set(ev.Path, ev.Rev, []byte(self))
if err != nil {
log.Println(err)
continue
}
w.Stop()
return seqn
}
}
return 0
}
func setC(cl *doozer.Client, path, body string, rev int64) {
_, err := cl.Set(path, rev, []byte(body))
if err != nil {
panic(err)
}
}